The present invention relates to the antiviral techniques making use of tea extracts having the effect of inactivating the viruses. More particularly it relates to a cup used for gargling for preventing cold caused by the influenza viruses, etc.; an antiviral mask which can prevent the infectious viruses from entering the mask wearer's system from the mouth and/or the nose by trapping the viruses floating in the air at a high rate and inactivating the trapped viruses; an antiviral filter which is capable of trapping the viruses floating in the ambient air at a high rate and inactivating the trapped viruses to clean the air; an antifungal, antibacterial and antiviral filter which can trap fungi, bacteria and/or viruses floating in the air to kill or inactivate the trapped fungi, bacteria and/or viruses, thereby to clean the air; an air cleaner; and an air cleaner-humidifier comprising said filter.